HHS NEWS
U.S. Department of Health and Human Services
FDA Public Health Advisory:
Interference Between Digital TV Transmissions and
Medical Telemetry Systems
(You are encouraged to copy and distribute
this Advisory)
March 20,1998
To: Director, Clinical/Biomedical Engineering
Risk Manager
Hospital Administrator
Nursing Home Director
Purpose of this Advisory
FDA has recently become aware of incidents involving digital
television (DTV) transmissions interfering with medical telemetry
systems that use TV channels. The purpose of this Advisory is to
alert you to the potential for this problem and provide
recommendations for your facility. In one case the telemetry
system was operating on a TV channel which had been unused for
many years but had been recently re-assigned by the Federal
Communications Commission (FCC) to a TV station in the vicinity
of the hospital for DTV. The new TV signal interfered with the
hospitals telemetry system and rendered it unusable. A second
hospital in the same city was also affected.
Many medical telemetry devices are operated under 47 CFR Part 15
of the FCC regulations. These devices are secondary users of the
radio-frequency (RF) spectrum. Licensed users such as television
stations are the primary users. As a secondary user, your
telemetry devices may be subject to interference from the primary
user at any time, but must not cause interference with the
primary user. If your telemetry devices are operating on
frequencies licensed to a primary user, you need to be aware of
the potential for interference and take any steps necessary to
avoid device malfunctions due to interference.
Medical telemetry devices have shared the TV broadcast spectrum
on channels 7-13 for many years. Last October FCC authorized the
operation of medical telemetry devices on much more of the TV
broadcasting spectrum. However, at this time most medical
telemetry systems are still believed to operate on the original
channels 7-13.
In the next six months, 10 major market areas for DTV will begin
transmitting signals on previously unused channels. Although
most of these first DTV stations will operate outside the channel
7-13 band, some will be broadcasting within that band. Many more
DTV stations will be on line by 2003 and could begin transmitting
at any time. The latest information on which channels have been
allocated to TV stations is listed by geographic location in an
FCC table of allotments. This table can be found on the FCC
website by going to www.fcc.gov/Bureaus/Engineering_Technology/
News_Releases/1998/nret8002.html (this address is upper/lower
case sensitive), then selecting DTV Table of Allotments (view in
either WordPerfect version or Acrobat version to see table
headings). Facilities using medical telemetry systems should
consult this table to determine the channel allotments for TV
stations in their area.
Recommendations
To address potential interference problems for medical telemetry
systems, FDA recommends that you work with the manufacturer of
your telemetry systems to:
- determine the channel/frequencies your telemetry systems
use; and
- consult the FCC table of allotments for DTV channels that
will be coming on line in your area.
If your telemetry systems are transmitting on channels that are
scheduled to be used by a local station, you should work with the
manufacturer of your telemetry systems to:
- consult with the local television stations to determine
when they plan to begin broadcasting on those channels; and
- change your telemetry channels to unused channels prior
to the expected broadcast date to avoid interference.
If you find that your telemetry systems are transmitting on
channels that will remain unused, you should not have a problem
due to DTV transmissions. However, you should periodically check
the FCC allotments to assure that those channels remain
available.
Reporting Adverse Events to FDA
The Safe Medical Devices Act of 1990 (SMDA) requires hospitals
and other user facilities to report deaths and serious illnesses
and injuries associated with the use of medical devices. Thus,
if interference with a medical device results in a death or
serious injury, it must be reported. We request that you follow
the procedures established by your facility for such mandatory
reporting.
If a telemetry system fails to function due to electromagnetic
interference or any other reason, it is a device malfunction.
Such malfunctions should be reported to the manufacturer or can
be reported directly to MedWatch, the FDA's voluntary reporting
program. Submit these reports to MedWatch: by telephone at
1-800-FDA-1088, by FAX at 1-800-FDA-0178, or by mail to MedWatch,
Food and Drug Administration, HF-2, 5600 Fishers Lane, Rockville,
MD 20857.
Getting More Information
If you have any questions regarding this Advisory which are
related to FDA issues, please contact Nancy Pressly, CDRH, Office
of Surveillance and Biometrics, HFZ-510, 1350 Piccard Drive,
Rockville, MD 20850, FAX 301-594-2968, or e-mail
nap@cdrh.fda.gov.
For additional information regarding FCC issues, please contact
Julius P. Knapp, FCC, Office of Engineering and Technology, 1919
M Street, NW, Washington, D.C., 20554, FAX 202-418-1944, or
e-mail jknapp@fcc.gov.
Additional copies of this Advisory can be found on the FDA
webpage at www.fda.gov/cdrh/safety.html. Further information
regarding electromagnetic interference and medical devices can be
found on our EMC webpage at www.fda.gov/cdrh/emc/index.html. If
interested in receiving Safety Alerts, Public Health Advisories
and other FDA medical device safety notices by e-mail when they
are released, subscribe to our listserver. To subscribe, send an
e-mail message to fdalists@archie.fda.gov. In the text of the
e-mail, put: subscribe dev-alert.
Sincerely yours,
D. Bruce Burlington, M.D.
Director
Center for Devices and Radiological
Health
March 25, 1998
Joint Statement of the
Federal Communications Commission and the
Food and Drug Administration
Regarding Avoidance of Interference Between
Digital Television and Medical Telemetry Devices
Certain medical telemetry devices, such as cardiac monitors, are
allowed to use TV broadcast channels that are unoccupied in their
geographic area. However, television stations are now
beginning to use these formerly unoccupied TV channels as they
transition to digital television service. When this occurs, the
digital signal may interfere with medical telemetry systems.
Such cases of interference have occurred recently and fortunately
no patients were significantly affected. The Federal
Communications Commission and the Food and Drug Administration
are taking steps to avert such cases of interference in the
future.
Medical telemetry devices have long shared the TV broadcast
spectrum on a secondary basis. This sharing can continue during
the implementation of digital television. However, it is
important to ensure that broadcasters, the health care community
and manufacturers of medical devices have adequate information
and take appropriate steps to avoid radio frequency
interference.
The FCC and the FDA are taking the following actions to address
interference to medical telemetry devices:
Federal Communications Commission:
- The FCC will ensure that TV broadcasters communicate with area hospital and other health care facilities to void interference to medical telemetry devices.
- The FCC is contacting manufacturers of medical telemetry devices to ask that they assist their customers in determining whether they may be affected by new DTV operations and, if appropriate, assist them in finding vacant channels.
- The FCC will provide easy access to information on spectrum sharing between DTV and medical telemetry devices on the FCC Internet web site. This will include a Fact Sheet and a listing of the channels that will be used for digital television service in each area.
Food and Drug Administration:
- The FDA is sending a Public Health Advisory to all U.S. hospitals and nursing homes, alerting them to the potential problem and providing advice on how to avoid future incidents.
- The FDA will work with medical device manufacturers to assure that medical devices are adequately labeled to alert users about the need to take steps to avoid interference.
Joint FCC & FDA:
- The FCC and FDA will explore the long term spectrum needs of medical devices so as to avoid future interference problems.
- The two agencies will work with equipment manufacturers and
the health care community to consider various long term
technology improvements that might ameliorate the
interference problem.
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